Establishment of a Fracture Initiation Pressure Prediction Model for vertical wells Based on the Elastoplastic Model

Abstract

Accurate determination of fracture initiation pressure in the presence of plastic zone around the borehole can assist engineers better manage expected fracture gradients. The classical models by Hubbert and Willis, and Haimson and Fairhurst did not account for the existence of this region in predicting fracture initiation pressure. In this paper, at first the elastoplastic stress solutions around the wellbore based on the Mohr-Coulomb criterion are presented. Second, based on the stress models, the fracture initiation pressure prediction model was established. Finally, the analytical model was applied to field data in order to verify the applicability of the developed model. The results from new elastoplastic model are very close to field data. Therefore, this model is recommended for forecasting the fracture initiation pressure analysis. Efficient prediction of fracture initiation pressure from vertical wellbores is therefore essential for petroleum industries to undertake effective drilling operation.